New federal clean-air guidelines will continue to reduce smog in the San Gabriel Valley and Whittier areas, but business owners struggling in the down economy feared any new rules would threaten their livelihoods, according to officials and business owners.

The new limits will likely put hundreds more counties nationwide in violation, a designation that will require them to find additional ways to clamp down on pollution or face government sanctions, most likely the loss of federal highway dollars.

The proposed guidelines were well- received at the South Coast Air Quality Management District in Diamond Bar, which oversees regulation of air pollution from Southern California businesses.

“Remember that, even though our air is much cleaner than it used to be, we still have the worst smog in the nation,” said AQMD spokesman Sam Atwood. “The AQMD strongly supports this proposal.”

But businesses barely hanging on were worried that they would be forced to spend more money to meet the new goals.

But coupled with a bad economy, the costs have him wondering if his business can survive beyond a few more months.

“As truckers we’ve always said we do not reject the idea of cleaning up the environment, but the means by which the government wants to accomplish that is just too stringent, especially in today’s economic environment,” he said.

If the new proposal is established, many communities that thought they were in compliance with earlier emissions laws will have to come into compliance again, said Mike Lewis, senior vice president of the West Covina-based Construction Industry Air-Quality Coalition.

“They’ve moved the goalpost,” he said. The tighter standards will cost tens of billions of dollars to implement, but will ultimately save billions in avoided emergency room visits, premature deaths, and missed work and school days, the EPA said.

Smog is a respiratory irritant that has been linked to asthma attacks and other respiratory illnesses. It is formed when emissions from burning gasoline, power and chemical plants, refineries and other factories mix in sunlight.

Representatives of the oil and gas industry, which said they have already invested $175 billion toward environmental improvements, were quick to say the proposal lacked “scientific justification.”

“There is absolutely no basis for EPA to propose changing the ozone standards promulgated by the EPA Administrator in 2008,” the American Petroleum Institute said in a statement.

Atwood said that academic studies show such cost increases from air regulation are nearly offset by the benefits of breathing clean air.

Atwood said the EPA will probably spend two years setting guidelines and implementation strategies. Then districts like the AQMD will enforce the guidelines, he said.

“In the meantime, we’ll try to map out strategies,” Atwood said.

The EPA proposal presents a range for the allowable concentration of ground-level ozone, the main ingredient in smog, from 60 parts per billion to 70 parts per billion.

It had been 84 parts per billion.

The stricter limit comes with additional costs, from $19 billion up to $90 billion a year by 2020, according to EPA. The Bush administration had put the cost to industry and drivers to meet its standard at between $7.6 billion to $8.5 billion a year.

Counties and states will have up to 20 years to meet the new limits, depending on how severely they are out of compliance. They will have to submit plans for meeting the new limits by the end of 2013 or early 2014.